The subject matter disclosed herein relates to turbines. Specifically, the subject matter disclosed herein relates to seals in gas turbines.
The main gas-flow path in a gas turbine commonly includes the operational components of a compressor inlet, a compressor, a turbine and a gas outflow. There are also secondary flows that are used to cool the various heated components of the turbine. Mixing of these flows and gas leakage in general, from or into the gas-flow path, is detrimental to turbine performance.
The operational components of a gas turbine are contained in a casing. The turbine is commonly surrounded annularly by adjacent arcuate components. As used herein, the term “arcuate” may refer to a member, component, part, etc. having a curved or partially curved shape. The adjacent arcuate components include outer shrouds, inner shrouds, nozzle blocks, and diaphragms. The arcuate components may provide a container for the gas-flow path in addition to the casing alone. The arcuate components may secure other components of the turbine and may define spaces within the turbine. Between each adjacent pair of arcuate components is a space or gap that permits the arcuate components to expand as the operation of the gas turbine forces the arcuate components to expand.
Typically, one or more slots are defined on the end faces of each arcuate component for receiving a seal in cooperation with an adjacent slot of an adjacent arcuate component. Typically, straight horizontal seal slots are present. The seal is placed in the slot to prevent leakage between the areas of the turbine on either side of the seal, and more particularly the gap defined between the arcuate components. These areas may include the main gas-flow path and secondary cooling flows. These seals need to allow sufficient machining and assembly tolerance for ease of assembly at the plant site. In many instances, an end gap is defined between one or more end regions of the seal and the slot, when the seal is disposed therein, or between end regions of adjacent seal segments.
Accordingly, it is desired to provide a seal design that provides more effective sealing of leakage at end gaps defined between one or more end regions of the seal and the slot or between end regions of adjacent seal segments. In addition, it is desired to provide a seal design that accommodates manufacturing and assembly tolerances.